1. Field of the Invention
The present invention relates to a pneumatic tire which can discharge static electricity generated in a vehicle body or a tire to a road surface.
2. Description of the Related Art
In recent years, for the purpose of reducing a rolling resistance which is deeply involved with reduction of fuel consumption of a vehicle, there has been proposed that a constituting member of the tire is formed by a nonconductive rubber. For example, in the case that a tread rubber is formed by a nonconductive rubber which is highly blended with silica, it is possible to reduce the rolling resistance, and it is possible to obtain an effect of improving a braking performance on a wet road surface (a wet braking performance). In order to enhance the effect of reducing the rolling resistance, it is effective to forma topping rubber of a carcass ply and a side wall rubber with a nonconductive rubber.
In the tire using the nonconductive rubber as mentioned above, a conductive route is formed by using a conductive rubber for preventing a problem, for example, a radio noise and the like. In the case that the topping rubber of the carcass ply and the side wall rubber are formed by the nonconductive rubber, it is necessary to form the conductive route in a side portion of the tire like Patent Documents 1 to 4. Patent Document 5 discloses a carcass in which a rubber sheet is interposed in a joint portion, however, neither relate to a tire which uses the nonconductive rubber, nor suggest a method for forming the conductive route in the side portion of the tire.